An Isil leader with "direct" links to the alleged ringleader of the Paris attacks was among 10 senior jihadists killed by US-led bombing raids in Iraq and Syria this month, the Pentagon has said.

Washington said the strikes were weakening the extremist group, which captured swathes of Iraq and Syria last year but has suffered a string of setbacks in recent weeks.

Colonel Steve Warren, spokesman for the coalition bombing Isil, named the dead man as Charaffe al-Mouadan.

He said the French national had been plotting additional acts of terror from Syria when he was hit by a US-led airstrike. Colonel Warren did not name the area in which Mouadan was killed.

Mouadan (26) was described as having a "direct link" with Abdelhamid Abaaoud, the Belgian jihadist thought to have masterminded attacks in Paris on November 13 before being shot dead by police days later.

The son of Moroccan parents, Mouadan grew up in the suburbs of Paris and was arrested in October 2012 while getting ready to leave with two neighbourhood friends for either Yemen or Afghanistan.

It was not immediately clear when he travelled to Syria, where he was known as Abu Souleymane, or what form his links to Abaaoud took.

Abaaoud served as an "emir of war" in the east Syrian province of Deir Ezzor, according to local activists and news reports, an unusually high rank for a fighter who hailed from Europe.

David Thomson, a leading expert on French jihadists, questioned whether Mouadan was as senior within Isil as the US claimed. But he confirmed that the jihadi was indeed thought to have links with members of the Paris attacks cell.

Colonel Warren said US-led air strikes killed nine other wanted Isil figures in the past month, including "several external attack planners, some of whom are linked to the Paris attacks".

One, named as Abdul Qader Hakim, was said to have facilitated Isil's external operations and also to have had links to the Paris attack network. He was killed in Mosul on December 26, Colonel Warren said.